[escaped]

Why

Fix #17. With USE_TZ = True, get_datetaken returned naive datetimes even
when the exif data contained OffsetTimeOriginal/OffsetTime or a
GPSDateTime, so Django warned about a naive datetime and stored the value in
the default timezone — the wrong instant for photos taken elsewhere.

Walkthrough

• DateTimeOriginal is combined with OffsetTimeOriginal (or the
  OffsetTime fallback) and returned with that UTC offset.
• GPSDateTime is treated as UTC, including the ...Z values ExifTool
  actually emits (the old code failed to parse those and ignored the tag).
• When DateTimeOriginal has no offset, an aware GPSDateTime is preferred
  over a naive original; a valid GPS value is also used when the offset is
  unparseable.
• A malformed offset now raises ExifError instead of silently returning a
  naive datetime (review finding).
• A naive datetime is still returned when the exif data has no offset at all;
  the README explains how to handle that with make_aware().

Changes

File(s)	Change Summary
exiffield/getters.py	offset/GPS-aware get_datetaken + parse helper
tests/test_getters.py	offset, GPS, precedence, malformed-offset and invalid cases
README.md	timezone behavior and a make_aware() recipe
CHANGELOG.md	note the fix under [Unreleased]

Testing

Red first: 5 of the new/updated cases failed against the old implementation
(AssertionError, plus ExifError for the ...Z GPS value); the
malformed-offset case failed against the first revision of the fix. After:

$ uv run pytest -q
78 passed, 1 xfailed in 5.08s
$ uv run ruff format --check . && uv run ruff check . && uv run mypy
17 files already formatted / All checks passed! / no issues found

%z parsing of the Z suffix was also checked on Python 3.10, the minimum
supported version.

CI on 48cb745: run 34694505570 — 14/14 jobs success.

PR breakdown

Stacked on the modernization branch test/e2e (PR #26). Merge in order.

#	PR	What it does	Status
1	#27	#23: missing orientation tag crash	Open
2	This PR	#17: timezone-aware get_datetaken	Open
3	#29	#6: document non-editable fields	Open
4	#30	#1: document and test deferred extraction	Open

[coveralls]

Coverage Report for CI Build 34898527593

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Coverage increased (+0.2%) to 98.454%

Details

• Coverage increased (+0.2%) from the base build.
• Patch coverage: 28 of 28 lines across 1 file are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	194
Covered Lines:	191
Line Coverage:	98.45%
Coverage Strength:	10.83 hits per line

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💛 - Coveralls

[escaped]

Review finding addressed in 48cb745: an unparseable offset now raises ExifError instead of silently returning a naive datetime, with a valid GPSDateTime still preferred when it is available. See the review record on #27.